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Struct mdbx::env::reclaiming_options

ClassList > mdbx > env > reclaiming_options

Garbage reclaiming options.

  • #include <mdbx.h++>

Public Attributes

Type Name
bool lifo = {false}

Public Functions

Type Name
bool operator!= (const reclaiming_options & other) noexcept const
reclaiming_options & operator= (const reclaiming_options &) noexcept
Copy assignment operator.
bool operator== (const reclaiming_options & other) noexcept const
constexpr reclaiming_options () noexcept
Constructs the default reclaiming options.
constexpr reclaiming_options (const reclaiming_options &) noexcept
Copy constructor.
reclaiming_options (MDBX_env_flags_t flags) noexcept
Constructs from the environment flags, extracting the reclaiming bits.

Public Attributes Documentation

variable lifo

bool mdbx::env::reclaiming_options::lifo;

LIFO policy for recycling a Garbage Collection items.

MDBX_LIFORECLAIM flag turns on LIFO policy for recycling a Garbage Collection items, instead of FIFO by default. On systems with a disk write-back cache, this can significantly increase write performance, up to several times in a best case scenario.

LIFO recycling policy means that for reuse pages will be taken which became unused the lastest (i.e. just now or most recently). Therefore the loop of database pages circulation becomes as short as possible. In other words, the number of pages, that are overwritten in memory and on disk during a series of write transactions, will be as small as possible. Thus creates ideal conditions for the efficient operation of the disk write-back cache.

MDBX_LIFORECLAIM is compatible with all no-sync flags, but gives NO noticeable impact in combination with MDBX_SAFE_NOSYNC or MDBX_UTTERLY_NOSYNC. Because MDBX will reused pages only before the last "steady" MVCC-snapshot, i.e. the loop length of database pages circulation will be mostly defined by frequency of calling mdbx_env_sync() rather than LIFO and FIFO difference.

This flag may be changed at any time using mdbx_env_set_flags().

Public Functions Documentation

function operator!=

inline bool mdbx::env::reclaiming_options::operator!= (
    const reclaiming_options & other
) noexcept const

function operator=

Copy assignment operator. 

reclaiming_options & mdbx::env::reclaiming_options::operator= (
    const reclaiming_options &
) noexcept

Returns:

A reference to this instance.

function operator==

inline bool mdbx::env::reclaiming_options::operator== (
    const reclaiming_options & other
) noexcept const

function reclaiming_options [1/3]

Constructs the default reclaiming options. 

inline constexpr mdbx::env::reclaiming_options::reclaiming_options () noexcept

function reclaiming_options [2/3]

Copy constructor. 

constexpr mdbx::env::reclaiming_options::reclaiming_options (
    const reclaiming_options &
) noexcept

function reclaiming_options [3/3]

Constructs from the environment flags, extracting the reclaiming bits. 

mdbx::env::reclaiming_options::reclaiming_options (
    MDBX_env_flags_t flags
) noexcept

Parameters:

The documentation for this class was generated from the following file mdbx.h++